SYSTEM FOR DETECTION OF SPACED DROPLETS

• US 20110311978A1
• Filed: 03/25/2011
• Published: 12/22/2011
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: QuantaLife, Inc. (Bio-Rad Laboratories Incorporated)
• Inventors: Hiddessen, Amy L., Makarewicz, Anthony J. Jr.
• Granted Patent: US 9,132,394 B2
• Time in Patent Office: Days
• US Class Current: 435/6.12
• CPC Class Codes: B01F 23/41 Emulsifying
• CPC Class Codes: B01F 33/3011 using a sheathing stream of a fluid surrounding a central stream of a different fluid, e.g. for reducing the cross-section of the central stream or to produce droplets from the central stream
• CPC Class Codes: B01L 2200/0689 Sealing
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0819 Microarrays; Biochips
• CPC Class Codes: B01L 2300/1822 using Peltier elements
• CPC Class Codes: B01L 2400/0478 pistons
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 2400/0622 distribution valves, valves having multiple inlets and/or outlets, e.g. metering valves, multi-way valves
• CPC Class Codes: B01L 3/0241 Drop counters; Drop formers making arrays for combinatorial libraries B01J19/0046; automation of dispensing for analysis G01N35/10
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502784 specially adapted for droplet or plug flow, e.g. digital microfluidics automatic analysis using a stream of discrete samples in a tube system G01N35/08
• CPC Class Codes: B01L 3/563 Joints or fittings in general F16L; Separable fluid transfer means to transfer fluids between at least two containers, e.g. connectors
• CPC Class Codes: B01L 7/52 with provision for submitting samples to a predetermined sequence of different temperatures, e.g. for treating nucleic acid samples amplification or hybridisation processes per se C12Q1/68; controlling sequential reactions for synthesis B01J19/0046
• CPC Class Codes: B01L 7/525 with physical movement of samples between temperature zones
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters

Abstract

System, including methods and apparatus, for detection of spaced droplets.

Claims

1. A detection system for droplet-based assays, comprising:

a tip;

a channel network defining a flow path for droplets, the flow path extending from the tip, through a confluence region configured to increase an average distance between droplets, and to an examination region disposed downstream of the confluence region; and

a detector operatively connected to the examination region,

wherein the flow path has a minimum diameter adjacent the confluence region.

2. The detection system of claim 1, wherein the minimum diameter is defined upstream of the confluence region.

3. The detection system of claim 1, wherein the flow path is defined in part by a droplet inlet channel that extends to the confluence region, and wherein the minimum diameter is defined by the droplet inlet channel.

4. The detection system of claim 3, wherein the diameter of the droplet inlet channel is less than or approximately equal to an average diameter of the droplets.

5. The detection system of claim 4, wherein the diameter of the droplet inlet channel is between about 90% and 100% of the average diameter of the droplets.

6. The detection system of claim 3, wherein the length of the inlet channel is between about one-half and three of an average diameter of the droplets.

7. The detection system of claim 6, wherein the length of the inlet channel is between one and two of the average diameter of the droplets.

8. The detection system of claim 1, wherein the droplet inlet channel has a uniform region of substantially uniform diameter that extends to the confluence region, and wherein the minimum diameter is defined by the uniform region.

9. The detection system of claim 8, wherein the droplet inlet channel includes a tapered region that tapers toward the confluence region, and wherein the uniform region extends from the tapered region to the confluence region.

10. The detection system of claim 9, wherein the tapered region and the uniform region are configured to arrange droplets in single file.

11. The detection system of claim 3, further comprising a droplet outlet channel that extends from the confluence region, and wherein the droplet outlet channel has about a same diameter as the droplet inlet channel.

12. The detection system of claim 3, further comprising a droplet outlet channel that extends from the confluence region, and wherein the minimum diameter of the droplet inlet channel is less than or equal to a diameter of the droplet outlet channel.

13. The detection system of claim 3, wherein a tapered region of the droplet inlet channel converges from a diameter of two or more average droplet diameters to a diameter of one or less than one average droplet diameters.

14. The detection system of claim 3, further comprising a droplet outlet channel that extends from the confluence region, and wherein the droplet inlet channel is at least generally parallel to the droplet outlet channel.

15. The detection system of claim 14, wherein an axis defined by the droplet inlet channel is within about 30 degrees of an axis defined by the droplet outlet channel.

16. The detection system of claim 3, further comprising a droplet outlet channel that extends from the confluence region and a dilution inlet channel configured to provide a dilution fluid, and wherein the dilution inlet channel is at least substantially parallel to the droplet outlet channel.

17. The detection system of claim 16, wherein an axis defined by the dilution inlet channel is within about 30 degrees of an axis defined by the droplet outlet channel.

18. The detection system of claim 16, wherein the droplet outlet channel has a diameter greater than a diameter of the dilution inlet channel.

19. The detection system of claim 1, wherein the channel network includes tubing and a discrete connector that provides fluid communication between three or more ends of the tubing, and wherein the minimum diameter is defined by the connector.

20. The detection system of claim 19, wherein each of the three or more ends defines a respective channel portion with an internal diameter that is greater than the minimum diameter.

21. The detection system of claim 1, wherein the confluence region is formed at a junction between a droplet inlet channel, a droplet outlet channel, and at least one dilution inlet channel configured to provide a dilution fluid.

22. The detection system of claim 21, wherein the at least one dilution inlet channel includes a pair of dilution inlet channels.

23. The detection system of claim 1, further comprising a light source configured to illuminate the examination region, wherein the detector is configured to detect light received from the examination region.

24. The detection system of claim 1, wherein the flow path extends to a waste receptacle configured to collect fluid that has passed through the examination region.

25. A detection system for droplet-based assays, comprising:

a tip;

a channel network defining a flow path for droplets, the flow path extending from the tip, through at least two confluence regions arranged in series, each confluence region configured to increase an average distance between droplets, and to an examination region disposed downstream of the confluence regions; and

a detector operatively connected to the examination region.

26. The detection system of claim 25, wherein at least one of the confluence regions includes only one dilution channel configured to supply a dilution fluid.

27. The detection system of claim 26, wherein at least two of the confluence regions include only one dilution channel configured to supply a dilution fluid.

28. The detection system of claim 26, wherein at least one other of the at least two confluence regions includes at least two dilution channels configured to supply a dilution fluid

29. The detection system of claim 25, wherein at least one of the confluence regions includes at least two dilution channels configured to supply a dilution fluid.

30. The detection system of claim 29, wherein at least two of the confluence regions include at least two dilution channels configured to supply a dilution fluid.

31. A method of detection for droplet-based assays, comprising:

driving droplets along a flow path from a tip, through a confluence region where a dilution fluid is introduced into the flow path, and through an examination region disposed downstream of the confluence region; and

detecting light from the examination region as droplets pass through,

wherein the flow path has a minimum diameter adjacent the confluence region.

32. The method of claim 31, further comprising a step of disposing the tip in contact with an emulsion, and a step of drawing droplets of the emulsion into the tip.

33. The method of claim 31, wherein the step of driving droplets includes a step of applying a negative pressure and a positive pressure on droplets with one or more pressure sources.

34. The method of claim 31, wherein the step of driving droplets includes a step of operating one or more syringe pumps.

35. The method of claim 31, wherein the step of driving droplets includes a step of arranging droplets in single file, and wherein the step of detecting light is performed as droplets that are in single file and spaced from each other pass serially through the examination region.

36. The method of claim 31, wherein the minimum diameter is defined upstream of the confluence region.

37. The method of claim 31, wherein the flow path is defined in part by a droplet inlet channel that extends to the confluence region, and wherein the minimum diameter is defined by the droplet inlet channel.

38. The method of claim 37, wherein the droplet inlet channel has a uniform region of substantially uniform diameter that extends to the confluence region, and wherein the minimum diameter is defined by the uniform region.